JP7220824B1 - Method for producing phenolic resin containing kraft lignin - Google Patents

Abstract

[Problem] When the kraft lignin (K) and the phenol resin have the same non-volatile content, the kraft lignin (K) has the optimum viscosity for application, good storage stability, peel test results, and temporary adhesion test results. K) To establish a method for producing the phenolic resin containing the phenolic resin. [Solution] An aqueous solution consisting of a phenol (P), a kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group is heated at a temperature of 85°C or higher. A method of producing a phenolic resin after heat treatment at temperature. [Selection figure] None

Description

The present invention is used as an adhesive for plywood, LVL (Laminated Veneer Lumber), etc., and is a method for stably producing a phenolic resin containing kraft lignin (K), which is a biomass material, so as to respond to environmental problems. It is about.

In recent years, environmental problems have been widely recognized by the international community as important social issues. Under such circumstances, in the field of chemistry, development using biomass materials is being actively carried out.
Patent Literature 1 is a publication that provides a production method for obtaining modified cellulose in a hydrophobic medium such as an organic medium or a resin with less mechanical force, and a modified cellulose having easy defibration properties.
As described above, a large number of publications have been published on the use of woody materials and herbaceous materials in terms of biology as biomass materials.

Examples of biomass materials other than cellulose include polylactic acid, polyamide, lignin, and the like. Lignin is being studied as a filler for epoxy resin moldings and films. In the field of adhesives, lignin is being investigated for use as a filler for hot-melt adhesives. Lignin is an aromatic polymer compound that constitutes 25-30% of wood, and its use in phenolic resin-based adhesives has been studied.

Examples of methods for producing pulp from wood include an acid-treated sulfite pulping method and an alkali-treated kraft pulping method. The sulfite pulping process yields acid-treated lignin with lignosulfonic acid as the main component, and its utilization is increasing. On the other hand, the kraft lignin obtained by the kraft pulping method is often used as fuel and recovered as heat, and utilization of kraft lignin other than heat recovery is not as advanced as that of acid-treated lignin.

JP 2021-006628 International publication 2016/098667 Special table 2014-516370 International publication 2017/163163

Patent Document 2 states in the abstract that "the impregnated plate includes a substrate and a resin composition impregnated into the substrate, and the resin composition contains a reaction product of lignin, phenols, and aldehydes. contains.”, but the lignin used here is acid-treated lignin.
Patent documents 3 and 4 use kraft lignin, but there is room for improvement in its performance.
Kraft lignin-containing phenol (K ) resin was sought.

When the non-volatile content of kraft lignin (K) and phenolic resin is about the same, it has the optimum viscosity for coating, good storage stability, peel test results, and temporary adhesion test results. Contains kraft lignin (K) It is to establish a manufacturing method of phenolic resin.

Heat treatment of an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group at a temperature of 85 ° C. or higher. and then a method for producing a phenolic resin.

When the non-volatile content of kraft lignin (K) and phenolic resin is about the same, the optimum viscosity for coating, good storage stability, peel test results, and temporary adhesion test results can be obtained. Contains kraft lignin (K) Since it is a method for producing phenolic resin, it is possible to produce plywood and LVL which are environmentally friendly and excellent in terms of workability and performance.

It is used as an adhesive for plywood, LVL (Laminated Veneer Lumber), etc. of the present invention, and a method for stably producing a phenolic resin containing kraft lignin (K), which is a biomass material, so as to respond to environmental problems. Here is an example.

The kraft lignin (K)-containing phenolic resin of the present application includes phenols (P), kraft lignin (K), and acids (A) having a pH of 1.8 or less at 0.1 mol/L excluding acids having a carboxyl group. The resulting aqueous solution is heat-treated at 85° C. or higher, then neutralized, and an alkali catalyst (C) and an aldehyde (F) are added thereto for reaction.
Phenols (P) used in the present invention include, for example, phenol, cresol, xylenol, nonylphenol, para-tertiary-butylphenol, para-secondary-butylphenol, naphthol, catechol, resorcinol, hydroquinone, methylhydroquinone, dimethylhydroquinone, etc.

Kraft lignin (K) is a material obtained by alkali-treating the lignin component contained in the pulp waste liquid of chemical pulping in the paper pulp manufacturing process.
The amount of kraft lignin (K) added is 10 to 60 parts by mass, more preferably 15 to 55 parts by mass as an active ingredient, per 100 parts by mass of phenols (P).
Kraft lignin (K) is commercially available as 100% and hydrous kraft lignin from Stora Enso Oyj.

An aqueous solution of the acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group includes, as inorganic acids, concentrated sulfuric acid, concentrated sulfurous acid, concentrated hydrochloric acid, concentrated nitric acid, phosphoric acid, organic Examples of acids include p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. In addition, it is better not to use an acid having a carboxyl group, because the viscosity of the kraft lignin (K)-containing phenolic resin is high and excellent adhesiveness cannot be obtained.
The amount of the acid (A) that has a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group is 0.05 to 10 parts by weight per 100 parts by weight of the phenols (P) as an active ingredient. , and more preferably 0.1 to 8 parts by mass.

The heat treatment temperature of the aqueous solution composed of the acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding phenols (P), kraft lignin (K), and acids having a carboxyl group is 85 ° C. or higher. It is preferably 90° C. or higher. The treatment time is 0.1 to 5 hours, more preferably 0.5 to 3 hours. By increasing the processing temperature, the processing time can be shortened.
After the heat treatment, it can be neutralized with an alkaline component so that the pH becomes 3 or more, and the next step can be performed. As the alkali component, the same compound as the alkali catalyst (C) described in the next section can be used. The amount of the alkali component added for neutralization is 0.05 to 1 part by mass, more preferably 0.1 to 0.8 part by mass, per 100 parts by mass of the phenol (P) as an active ingredient.

The alkali catalyst (C) used in reacting the phenols (P) and the aldehydes (F) is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, water Basic catalysts such as magnesium oxide, trimethylamine, triethylamine and tributylamine can be used as appropriate.
The amount of the alkali catalyst (C) to be added is 1.5 to 40 parts by mass, more preferably 6 to 33 parts by mass as an active ingredient, per 100 parts by mass of the phenol (P).
In the kraft lignin (K)-containing phenolic resin of the present application, the alkali catalyst (C) can be added in multiple steps if the reaction generates a lot of heat. Also, in order to save time for dissolution, an alkali catalyst (C) dissolved in water in advance can be used.

As the aldehydes (F), any aldehydes (F) that can be used in the production of phenolic resins can be used.
For example, formaldehyde, paraformaldehyde, trioxane (metaformaldehyde) and the like can be used alone or in combination of two or more.
The amount of aldehydes (F) added as an active ingredient is 40 to 100 parts by mass, more preferably 50 to 90 parts by mass, per 100 parts by mass of phenols (P).
As with the alkali catalyst (C), aldehydes (F) dissolved in water in advance can also be used.

Phenolics (P), kraft lignin (K), 0.1 mol/L of an aqueous solution consisting of an acid (A) with a pH of 1.8 or less excluding an acid having a carboxyl group is heat treated, and after neutralization of the alkaline component, phenol The reaction of the alkali catalyst (C) used in the reaction of the group (P) and the aldehydes (F) can be carried out in one step, but since this reaction is an exothermic reaction, it is carried out in multiple steps as described above. The reaction can also be performed separately. Moreover, the total of the alkali component for neutralization after the heat treatment and the alkali catalyst (C) can be added at the same time.
For example, when the reaction is performed in one step, an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 0.1 mol/L and excluding an acid having a carboxyl group is 1.8 or less. After heat treatment and neutralization of the alkaline component, the necessary aldehydes (F) are added, the total amount of the alkaline catalyst (C) is added, and the reaction is carried out by heating.
The reaction temperature is 70-110° C., more preferably 80-100° C., and the reaction time is 1-8 hours, more preferably 6-7 hours.

After completion of the reaction, an alkali component can be added for pH adjustment. The amount of the alkaline component added for pH adjustment is 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, per 100 parts by mass of the phenol (P) as an active ingredient.

Kraft lignin (K)-containing phenolic resin of the present application traps unreacted aldehydes (F) after reacting phenols (P) with aldehydes (F), so urea and its derivatives, resorcin can be added. The amount of these components to be added is 0 to 60 parts by mass, more preferably 0 to 50 parts by mass, per 100 parts by mass of the phenol (P) as an active ingredient.
Moreover, water can be added to the kraft lignin (K)-containing phenol resin for viscosity adjustment. The amount of water to be added is 1 to 20 parts by mass, more preferably 5 to 15 parts by mass, per 100 parts by mass of the phenol (P). At this time, the non-volatile content of the kraft lignin (K)-containing phenolic resin is 40 to 50%. If it is out of this range, there is a possibility that good results of the decompression/pressure peeling test and temporary adhesion test cannot be obtained.

An adhesive composition for producing plywood and LVL is generally produced by adding an additive to a phenolic resin and using a homogeneous adhesive composition. 100 parts by mass of phenol resin containing water, 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, 1 to 20 parts by mass, more preferably 5 to 15 parts by mass of wheat flour, calcium carbonate 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, 1 to 20 parts by mass of wheat flour, more preferably 5 to 25 parts by mass, 0.5 to 20 parts by mass of sodium carbonate, more preferably 1 By adding up to 10 parts by mass and homogenizing, an adhesive composition for producing plywood and LVL can be obtained.

<Regarding the production method of LVL>
The LVL 13-ply will be explained. One side of the adherend is coated with an adhesive composition in an amount of 100 to 300 g/m 2 , more preferably 120 to 200 g/m 2 . All are superimposed face/core/back parallel to the wood grain, and the pressure is applied at 0.4 to 1.2 MPa, more preferably 0.6 to 1.0 MPa, for 5 to 35 minutes, more preferably 10 minutes. Cold pressing is done for ~30 minutes.
Next, a hot pressure press heated to 100 to 170 ° C., more preferably 110 to 160, the pressure is 0.4 to 1.2 MPa, more preferably 0.6 to 1.0 MPa, and the pressing time is 800. It can be obtained by pressing at ∼2200 seconds, more preferably 1000-2000 seconds.

The present invention will be described in more detail below with reference to examples, comparative examples, test examples, and the like, but these are specific examples and are not intended to limit the invention in particular.

pH measurement pH measurement was carried out using a pH meter, product name: HM-25H, manufactured by Toa TK Corporation.

pH Measurement of 0.1 mol/L Aqueous Solution Each 0.1 mol/L aqueous solution was prepared, and the pH was measured using the above pH meter. Tables 1 and 2 show the results.

Treatment method of phenol (P), kraft lignin (K), and acid (A) aqueous solution in Example 1 100 g of phenol, 50 g of 63%-hydrous kraft lignin (31.5 g of active ingredient), 1 g of 20%-sulfuric acid ( 0.2 g of active ingredient) was weighed into a container, and stirred for 1 hour after the temperature inside the container reached 110°C. At the stage of returning to room temperature, 0.52 g (0.25 g of active ingredient) of 48% sodium hydroxide aqueous solution, which is an alkaline component, was added so that the pH was 3 or more and homogenized.

Phenols (P), kraft lignin (K), acid (A) aqueous solution treatment method in Examples 2 to 8 and Comparative Examples 1 to 10 Phenols (P) in Example 1, kraft lignin (K ), the phenols (P) of Examples 2 to 8 and Comparative Examples 1 to 10, kraft lignin (K), An acid (A) aqueous solution was treated.
In Example 8, 100% kraft lignin was used, almost no water was present in the system, and the treatment temperature could be 100°C or higher, so the treatment was carried out at 120°C. The processing time was 0.5 hours. After the treatment was completed, the non-volatile content was approximately matched to that of the other examples by adding 23 g of water. The values in parentheses in Tables 3 and 4 represent the mass of the active ingredient.

Method for producing phenolic resin containing kraft lignin of Example 1 In the liquid obtained by the method of treating phenol (P), kraft lignin (K), and acid (A) aqueous solution of Example 1, 37%- 170 g of formaldehyde aqueous solution (62.9 g of active ingredient), 45 g of 48%-sodium hydroxide aqueous solution (21.6 g of active ingredient) and 70 g of water were added and reacted at 90° C. for 6 hours.
After that, 15 g of 48% sodium hydroxide aqueous solution (7.2 g of active ingredient) was added to adjust the pH, 20 g of urea was added to trap unreacted aldehydes (F), and 10 g of water was added to adjust the viscosity. to make it uniform.

Methods for producing kraft lignin-containing phenolic resins of Examples 2-8 and Comparative Examples 1-10 A phenolic resin containing kraft lignin was prepared.

About 1.5 g of a sample was weighed into an aluminum pan having a non-volatile content diameter of 65 mm, a bottom diameter of 55 mm, a depth of 20 mm and a thickness of 0.05 mm to obtain the initial weight. An aluminum pan with a sample placed thereon was placed in a constant temperature layer previously adjusted to 105±1° C., and the dry weight after 3 hours was measured. The weight after drying was divided by the initial weight, and the non-volatile content was expressed as a percentage. Tables 5 and 6 show the results.

Viscosity The viscosities of the liquids obtained by the methods for producing kraft lignin-containing phenolic resins of Examples 1 to 8 and Comparative Examples 1 to 10 were measured according to JIS-Z-8803. The viscometer was a single cylindrical rotational viscometer manufactured by Shibaura Systems Co., Ltd., trade name: Vismetron VG-A1. Moreover, as a measurement condition, No. Measured at 2 rotors, 60 rpm, 60 seconds value, 23±1° C., and the measured value was taken as the viscosity. The optimum viscosity range for application is 200-250 mPa·s. If the viscosity is high, the viscosity can be adjusted by adding water, but in that case the non-volatile content changes, and it is known that good results of the vacuum pressure peel test and the temporary adhesion test cannot be obtained.
Tables 5 and 6 show the results.

Storage Stability The liquids obtained by the methods for producing kraft lignin-containing phenolic resins of Examples 1 to 8 and Comparative Examples 1 to 10 were stored in an environment of 20±5° C. for 2 weeks, and the viscosity after storage was measured. . Tables 5 and 6 show values obtained by dividing the viscosity after storage by the initial viscosity. As for the judgment criteria, values between 0.9 and 1.5 are considered acceptable, and deviations from this value are considered unacceptable.

Preparation of the adhesive composition of Example 1 100 g of the phenolic resin of Example 1, 25 g of water, 10 g of wheat flour, 25 g of calcium carbonate, and 5 g of sodium carbonate were weighed into a stirring vessel, and Shinto was equipped with stirring blades. The adhesive composition of Example 1 was obtained by stirring for 30 to 60 minutes using Three-One Motor BL600 (trade name, manufactured by Kagaku Co., Ltd.).

Preparation of adhesive compositions of Examples 2 to 8 and Comparative Examples 1 to 10 Adhesives of Examples 2 to 8, Comparative Example 1, and Comparative Examples 5 to 6 were prepared in the same manner as the preparation of the composition of Example 1. A composition was made. In Comparative Examples 2 to 4 and Comparative Examples 7 to 10, the viscosity of the liquid obtained by the method for producing a kraft lignin-containing phenolic resin was not within the appropriate range, so adhesive compositions were not produced.

3.8 mm thick cedar was selected. The LVL having a 13-ply structure was applied with pressure so that the thickness after lamination was 45 mm. The moisture content of these materials is 6% or less, the area of each material is 300 mm x 300 mm, the temperature of each material is 23°C, and the working environment is 24°C.
The adhesive composition was applied to one side of the cedar wood in an amount of 220 g/m 2 , and all of them were superimposed in parallel to the wood grain so as to form face/core/back. Cold pressing was performed at 0.8 MPa for 20 minutes.
Next, a hot press was heated to 135.degree.
A vertical two-stage high-pressure press S2D-100 manufactured by Itsumi Co., Ltd. was used as a hot press.

Decompression and pressure peeling test A decompression and pressure peeling test was conducted according to the usage environment A of the Japanese Agricultural Standards for laminated veneer lumber. A test piece of 75×75 mm square was immersed in water at room temperature, depressurized to 0.085 MPa or more for 5 minutes, and further pressurized to 0.51±0.03 MPa for 1 hour. After repeating this treatment twice, it was placed in a constant temperature dryer at 70° C.±3° C. and dried to a range of 100 to 110% of the mass before the test. After repeating the above treatment twice, the peel length was measured and the peel rate was calculated. Criteria for judgment are a peeling rate of 5% or less and a peeling length of one adhesive layer of 1/4 or less. Those that satisfied these criteria were evaluated as pass (: ◯), and those that did not satisfy these criteria were evaluated as disqualified (: x). Tables 5 and 6 show the results.

Temporary Adhesion Test Two sheets of MDF (medium-density fiberboard) of 65 mm×145 mm×4 mm thickness and one sheet of MDF of 45 mm×145 mm×9 mm thickness were prepared. On both sides of a 9 mm thick MDF, 40 g/square of the adhesive composition liquid of Examples and Comparative Examples is applied to both sides, and both ends of the short side and one end of the long side are aligned to form a 4 mm thick MDF. Two sheets were superimposed one on top of the other.
At 23° C., a pressure of 0.8 MPa was applied for 10 minutes, and after the pressure was released, a width of 25 mm was cut out.
The jig was inserted into a gap prepared in advance, and the tear adhesive strength was measured at a speed of 10 mm/min in an atmosphere of 23° C. using Tensilon (trade name, manufactured by A&D Co., Ltd.). n=4 means. As for the judgment criteria, 150 N or more is acceptable, and less than 150 N is unacceptable. Tables 5 and 6 show the results. In Comparative Examples 5 and 6, the decompression and pressurization peeling test failed, so the test was not conducted.

Heat treatment of an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group at a temperature of 85 ° C. or higher. After that, Examples 1 to 8, in which phenolic resins were produced, all passed the viscosity, storage stability, vacuum pressure peeling test, and temporary adhesiveness test.

Heat treatment of an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group at a temperature of 85 ° C. or higher. Then, among the methods for producing phenolic resin, Comparative Example 1, which does not use kraft lignin, passed the viscosity, pressure reduction and pressure peeling test, and temporary adhesion test, but failed the storage stability. . It was shown that storage stability is poor when kraft lignin is not used.

Heat treatment of an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group at a temperature of 85 ° C. or higher. Then, among the methods for producing a phenol resin, Comparative Example 2 in which an aqueous solution consisting of an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group is not added, Comparative Example 3 using oxalic acid, which is an acid having a carboxyl group, and in which the amount of oxalic acid added was particularly small, Comparative Example 6 using fumaric acid and tricarballylic acid, Comparative Example 7, and treatment with sodium hydroxide. In Comparative Examples 8, 9, and 10, the viscosity is higher than the appropriate viscosity, suggesting that the kraft lignin (K) is not sufficiently treated.

Heat treatment of an aqueous solution consisting of phenols (P), kraft lignin (K), and an acid (A) having a pH of 1.8 or less at 0.1 mol/L excluding an acid having a carboxyl group at a temperature of 85 ° C. or higher. Then, among the methods for producing phenolic resin, oxalic acid, which is an acid having a carboxyl group, was used, and Comparative Examples 4 and 5, in which the amount added was larger than that in Comparative Example 3, had a proper viscosity. However, the decompression and pressure peeling test failed, and the temporary adhesion test was not performed.

Claims (1)

10 to 60 parts by mass of kraft lignin (K) as an active ingredient per 100 parts by mass of phenols (P), 0.1 mol/L excluding acids having a carboxyl group, an acid having a pH of 1.8 or less ( A) is a method in which an aqueous solution containing 0.05 to 10 parts by mass as an active ingredient is heat-treated at a temperature of 85° C. or higher to produce a phenolic resin.